Apparatus for fractionation of hydrocarbons



May 12, 1931. c. P. DUBBs APPARATUS FOR FRACTIONATION 0F HYDROCARBONS Filed Jan. 14, 1926 Patented May 1.2, 1931 UNITED STATES PATENT OFFICE CARBON P. DUBBS, WILMETTE, ILLINOIS, .ASSIGNOR TO UNIVERSAL OIL PRODUCTS COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF SOUTH DAKOTA APPARATUS FOR FRACTIONATION OF EYDBOCARBONS Application mea' January i4, 192s.- sriai 116181,15?.

lect certain ranges of boiling points, it has been found that these separated products are more or less contaminated with a substantial portion of higher and lower boiling point products, which in most instances is unde'- sirable. For instance, assume that a standard still is charged with crude petroleum containing gasoline, kerosene, gas oil, etc. Byfthe application of external heat, the oil is progressively distilled and the released vapors con-vv densed and collected, the lowest boiling point vapors distilling of rst, and the yvapors of higher boiling points following progressively. f

aF or instance, say a gasoline cut will consist of that portion of oil distilling oil from the lowest temperature up to 437 F. This.

cutis condensed and separately collected; the cut taken above 437 F. is known as the kerosene cut.

In the ordinary apparatus, the gasoline will be found to contain boiling'points higher than 437 F., and the kerosene cut will be found to contain boiling points lower than 437 F. In oth'erwords, there will be some kerosene in the gasoline cut,l and some gaso- Iline in the kerosene cut. Heretofore, thesel were known as'crude cuts ofkerosene and gasoline, and were redistilled to lseparately free the gasoline from the`= kerosene and to free the kerosene from the gasoline.

In recent practice, recti-fying' columns, have been put on-the crude still to accom-- plish the same purpose on the'fflrst distillation, thus avoiding redistillatlon of these cuts. In continuous tube stills the operation is somewhat different. In this case the total oil to be distilled olf is` vaporized, and the mixed va ors passed through rectlfymg columns or ephlegmators and the dlferent cuts rately condensed.

fractionally condensed therein. As an illustration, if it is desired to distill the gasoline and kerosene cuts from the crude oil, the crude oil is subjected to a temperature at whichy both of these cuts are vaporized. These vapors, having a, wide range of boiling points, are then passed through the rectifying columns where the portions having boilmg points higher than kerosene, are first condensed and withdrawn separately, and the remaining vapors passed to a` second rectifying column in which the portions containing boilmg points formin the kerosene are condensedand collecte separately.

Iheremaining vapors containing boiling points forming gasoline, are then withdrawn, condensed and separately collected.

In some cases, it is only desirable to obtain and collect gasoline, while in other cases it is des1rable to collect separately the gasoline, kerosene, and sometimes gas oil.'

The process and apparatus for fractionation hereinafter described, will be found to be suitable for all of the above purposes. If

more than a gasoline cutis desired, then more dephlagmating or fractionating columns will have to be used in proportion to the number of cuts of different boiling points desired.

It will be apparent to those skilled in the art, that great savings will be made by havino' a rectifying column so designed as to brmg about an efficient separation of the different fractions for use with distilling and cracking processes, which will obviate the necessity of redistilling these condensed vapors; 'It is highly desirable. to provide a rectfying column that will eliiciently -func- 4.tionjto condense therein only those portions ofigthe vapors having boiling points higher than those vvbelonging to the gasoline -fra'ctions while leaving the gasoline fractions in the' vapor phase to be withdrawn and `sepa- In the drawings, Fig. 1 is a diagrammatic side elevational view-in vertical section, of a rectifying column. Fig. 2 is a cross sectional view taken on line 2-2 of Fig. 1. Fig. 3 is a cross sectional view taken on line 3-3 of Fig. 2.

Referring more in detail to the drawings,

1 designates the outer shell having the head 2. Disposed vertically in the height of the shell 1 are helices 3 contained in an inner shell .4. The outer edge of the helices 3 is solidly joined to the inner wall of the inner shell 4 so that no vapors can pass between the outer edge of the helices and the inner wall of shell 4. A core rod 7 projects down- Wardly through the center of the helices for the purpose of forming a supporting connection. The inner shell 4 may be iianged as shown at 8 to it between the ianges of the shell 1 and head 2. It will be immediately apparent that when the head 2 is removable,

. vapor outlet pipe controlled by valve 16. 17

designates a liquid levelk gauge and 18 the approximate liquid level line y,in the rectifying column. 4 At various intervals throughout the height of the helices may be interposed bailes 19. The operation of the rectifying column should be apparent from the foregoing description. e

The mixture of vapors entering the rectifying column through the vapor inlet 9 are discharged into the bottom section of the helices 3. It will be noted that the liquid level isshown in the drawing below this vapor inlet 9, but suiliciently high so as to cause the lower portion of the helices 3 to be submerged therein. The object of this is to kee with liquid and thus prevent any vapors entering that section, since such vapors would not be compelled to travel up through the helices. The apparatus of course, can be operated eiciently without any liquid level in this part of the chamber 4it' desired. As the vapors are forced totravel upwardly in a helical path around the helices, they are de,- creased in temperature andv condensation of gart of the. vapors continuously takes place.

y the time those vapors which are still uncondensed, reach the top of the helices, all of the vapors having boiling` points higher than those desired, have been condensed. Theref fore, the vapors withdrawn from the rectiv fying column through theJ pi e 15 are of the desired low boiling points. he condensate in the rectifying column contains more or less of that portion hiving boiling vpoints lower than those it is desired to condense in the rectifying column, but as these condensed vapors ilow back down the surface `of the helices, they are progressively subjected to vapors in this part of the rectifyin the portion below the helices filled ltion o higher heat so that' any low boiling point portions contained therein are revaporized y the hot ascending vapors so that by the time the condensate reaches the bottom of the spiral, it has been freed of substantially all that fraction having the desired low boiling point. The function of the baille plates 19 is to direct the vapors to the outer periphery of the spiral.

It will be noted that the surface of the spiral helices is shown as corrugated in the drawing. This is not necessary, but may be preferable. It is also to be noted that the spacing of this helix gradually grows smaller in an upward directlon, for the reason that since part of the vapors are condensed as they pass upward about the helix,"the remalning volume of vapors 'is smaller, and tol maintain the same velocity, it is necessary to decrease the space betweep the helices. It is of considerable advantage to have the spiral 3 made of a thin metal of lgreat heat conductivity so that the heat from the ascending vapors can bereadily transmitted from one side of the spiral to the film of liquid flowing over the upper side, thus promoting the evaporation of the light'ends of this condensate.-

If the material being cracked, contains more or less ofa product havin boiling points similar to those produced y cracking, it may be fed directly into the top of the fractionating columnthrough the inlet pipe 13, but preferably this oil should be preheated and brought -to the temperature of the column before being discharged therein. I? it is not desired to preheat such oil, pipe 13 should preferably enter the rectifying column at approximately the center of the spiral. By doing this, the light ends will be vaporized from the cooling material and pass out as vapors from the dephlegmator whilel the heavier ends will flow downwardly along the surface of the helix, together with any condensate. The rectifying column may be maintained under atmospheric pressure, superat-mospheric pressure, or under vacuum.

The rectifying column should be so designed, that the velocity 'of the vaporsthrough the spiral will not be sutlicient to pick u by entrainment any substantial porthe condensate. f

The fractionating column may be say five feet in diameter and forty feet high more or less. The spacing at the lowest part of the helix may be say eight inches more or less, progressively decreasing until the space at the upper part of the helix is say five inches.

The charging stock treated per day may be 1,000 barrels, and the vapors entering the rectifying column through the pipe 9 may be 830o F. more or less. The vapors discharging through the pipe 15 may be at a temperature 'of say 350 F. more or less.

The above igures are merely illustrative.

The corrugation instead of running in the same direction as the spiral, may extend at right angles to impede the downward ow of the condensate.

I claimas my invention:

l. Apparatus for rectiyin hydrocarbon oil vapors, comprising in com ination a vertical cylindrical shell, means near the bottom thereof for admitting vapors'to be rectified, means near the top thereof for withdrawing uncondensed vapors and gases, means also near the top thereof for discharging a cooling liquid into said shell, a baiile in said shell comprising a thin strip of metal of corrugated cross section, a central vertical core rod for supporting said balile, the inner edge of said balile being wrapped or wound around said core rod forming a series of spaced convolutions, the spacing of said convolutions being decreased toward the top of said rod, and the strip extending radially from said rod at all points of'contact there- "with, the outer edge of said strip being in contact with said shell, the corrugations of said strip being parallel and concentric and extending substantially the full length of said strip.

2. In a rectifier for hydrocarbon oils, a helical baiile provided with a plurality. of concentric, parallel corrugations extending the full length of said baile, a vertical rectangular intercoastal baille positioned between the convolutions of the helical baille with 'its upper edge contacting the lower portions of said corrugations, and with its lower edge contacting the upper portions of said corrugations, said corrugations providing apertures below the Vertical balile for passage of cooling liquid and apertures above thevertical baile for the passage ofjuncondensed vapors.

3. Apparatus for rectifying hydrocarbon oil vapors, comprising in combination, a vertical cylindrical shell, means near the bottom thereof for admitting vapors to be rectified, means near the top thereof for withdrawing uncondcnsed vapors and ases, means also near the top thereof for disc arging a cooling liquid into said shell, a baille in said shell, comprising a thin strip of metal of corrugated cross section, a central vertical core rod for supporting said baille, the inner edge of said baffle being wrapped or wound around said core rod forming a series of spaced convolutions, and the stri extending radially from said rod at all polnts of contact therewith, the outer edge of said strip being in contact with said shell, the corrugations of said strip being` parallel and concentric and extending substantially the full length of said stri.ARBON P DUBBS 

